Role of particle stimulated nucleation in recrystallization of hot extruded Al 6061/SiCp composites

Studies on texture and microstructure evolution in hot extruded Al 6061 aluminium alloy reinforced with uncoated and nickel coated SiCp were carried out by electron backscattered diffraction technique. Textures of both the alloy and its composite with nickel coated SiCp do exhibit strong beta fiber with its axis parallel to the direction of extrusion. In addition to the dominant cube texture (001)< 100 >, fully recrystallized grains with partially equiaxed structure have been observed in the alloy reinforced with uncoated SiCp. The recrystallization texture of this composite can be attributed to the particle stimulated nucleation (PSN) due to the presence of SiCp with size less than 5 mu m. Under these conditions, the low value of Zener-Hollomon, Z (similar to 10(12) s(-1)) confirms that PSN is one of the dominant mechanisms for recrystallization and is governed by formation of deformation zone rather than stored energy.